Déjà_vu: Remote RTSCTS supported but Local RTSCTS not supported BOL

#### Issue details
When local radio (base/GCS) is set to use RTS/CTS, MP tries to connect without RTS/CTS to remote. Near the the end of timeout, it tries to use RTS/CTS for connecting, and connection will be established. Disabling the feature from local radio "solves" the problem.

#### Version
1.3.37

#### Platform
[ ] All
[ ] AntennaTracker
[ ] Copter
[ x ] Plane
[ ] Rover
[ ] Sub

#### Hardware type
pixhawk

#### Logs

INFO MissionPlanner.MAVLinkInterface - MAVLINK: 1 wait time out btr 0 len 0
INFO MissionPlanner.MAVLinkInterface - MAVLink readpacket read error: System.TimeoutException: Timeout
at MissionPlanner.MAVLinkInterface.d__241.MoveNext()
bps 0 loss 0 left 0 mem 47,9150390625 mav2 False sign False mav1 0 mav2 0 signed 0
INFO MissionPlanner.MAVLinkInterface - set giveComport current True new False
INFO MissionPlanner.Comms.SerialPort - COM10 RtsEnable True
INFO MissionPlanner.MAVLinkInterface - 779 Start connect loop

Start with the MissionPlanner.MAVLinkInterface connect loop and readPacketAsync entries shown in the log, then inspect MissionPlanner.Comms.SerialPort where RtsEnable is set. Reproduce the Plane connection using local RTS/CTS on the reported hardware and compare the initial connection behavior. Done should mean the local RTS/CTS setting is applied consistently instead of only near the timeout.

Written by the indexing model from the issue text.